My casual stove of choice is an empty baked bean can (small size). Holes drilled around the cylinder just above the base (to let the air in) and just below the open top (to let the smoke, etc, out when there's a pan, or whatever, effectively closing the top).
I have a cheap, lightweight steel mug to use as a pan with this and it's fuelled with hexamine tablets.
The more robust version (for when I actually expect to do more than make a cup of tea) features a heavier-gauge mug - or a light cookset if camping - and a simple cylinder-mounted gas stove.
I used to use a standalone meths burner with a trivet, sometimes, but the whole kit (stove + bottle) is heavier than system 1, above. What put me off for good, though, was the sight of burning meths trickling through the undergrowth when I accidentally knocked the whole thing over. Luckily, it was a very wet day and there was not too much meths to be chased around and stamped on! Given the increasing propensity of forests and peat moors to catch fire, these days, I'm more cautious than ever. No more uncontrolled liquid fuels for me in the great outdoors and I'm much more careful, too, about the stability of whatever arrangement I do use!